1. Field of the Invention
The present invention relates to a belt-type door opening and closing drive apparatus to be used such as for opening and closing the doors of an elevator or an automatic door of stores.
2. Description of the Related Art
For example, following apparatuses are conventionally known as a belt-type door opening and closing drive apparatus for opening and closing the doors of an elevator. An apparatus reduces the output of a motor with (multistage) belts and pulleys and allows the reduced output to drive the door opening and closing belt (a cog belt generally referred to as a timing belt), thereby opening and closing the door. Another apparatus allows the reduced output of a geared motor to drive the door opening and closing belt, thereby opening and closing the door.
The opening and closing drive apparatus for opening and closing the door of an elevator is generally provided with a sensor for detecting a person or some object caught in the door opening. In the event the sensor has detected a person or an object caught in the door opening, the drive apparatus is adapted to open the door of the elevator.
Of the conventional drive apparatuses described above, the one which transmits the output of the motor to the door opening and closing belt (the timing belt) in combination of the belts and pulleys is to reduce the rotational rate of the motor by placing pulleys having different diameters on the input and output sides. To set a higher reduction ratio, this requires generally a multistage configuration of the apparatus (since there is a limit to the reduction in diameter of the input pulley and the increase in diameter of the output pulley). This in turn makes it difficult to provide a compact and an inexpensive apparatus.
On the other hand, the one that employs the geared motor can provide a more compact apparatus than that employing a combination of the multistage belts and pulleys. However, the apparatus presents a problem of providing a high level of noise and causing its mechanical safety function not to work in the event of the sensor failure or the like, as described later.
The present invention was developed in view of the afore-mentioned problems. It is therefore an object of the present invention to provide a drive apparatus for opening and closing the doors of an elevator, the apparatus being capable of providing a mechanical safety function in the case of an accident.
The present invention provides the following belt-type door opening and closing drive apparatuses to thereby overcome the aforementioned problems. That is, provided is a belt-type door opening and closing drive apparatus for allowing an output of a motor unit to drive a belt to thereby open and close a door. The apparatus is adapted such that between the motor unit and the belt, a planetary roller unit having a sun roller, a planetary roller circumscribing the sun roller, and a ring roller with which the planetary roller is inscribed in is interposed. The planetary roller unit receives the output from the motor unit and an output from the planetary roller unit is transmitted to the belt.
In the present invention, the planetary roller unit is interposed as power transmission means between the motor unit and the belt for opening and closing a door. (Here, the belt is a cog belt which is called a timing belt. However, the present invention is not limited to the cog belt. For convenience, the belt is hereinafter referred to as a timing belt.) The planetary roller unit provides a compact shape and a high reduction ratio, thereby allowing the entire drive apparatus to be made easily compact.
In addition, the planetary roller unit itself transmits power by means of mutual rotations (frictional rotations or traction rotations) of the sun roller, the planetary roller, and the ring roller, thereby providing a quiet operation.
Furthermore, the planetary roller unit makes full use of preventing the vibration from being transmitted between the input and the output side by means of the contact surfaces between the rollers. That is, the planetary roller unit cuts off the vibration produced by the motor unit of the input side and otherwise transmitted to the timing belt, and the vibration generated by the timing belt (the doors of the elevator) to be otherwise transmitted to the motor unit. Accordingly, this makes it possible to prevent the occurrence of the so-called resonance phenomenon in which objects vibrating at natural frequencies different from each other are affected by each other to produce a greater vibration or noise than that produced by each of the objects. Consequently, it is made possible to significantly increase the quietness of the entire drive apparatus.
Furthermore, the planetary roller unit is characterized by its structure that will cause each roller to slide upon application of an excessive load to the output side, thereby allowing no more torque to be transmitted. If the sensor system fails to detect a person or an object caught in the opening between the doors and stop or reverse the rotation of the motor shaft, leading to a situation where the motor unit continues to work with the person or object being caught in the opening, the present invention makes it possible to prevent the excessive torque from being acted upon the person or object being caught in the opening. In other words, the present invention can make full use of the mechanical safety function in the event of an accident. This function is effective particularly when a special emphasis is placed on the response speed of opening and closing the door and therefore a relatively high torque is required of the motor.
Incidentally, the motor unit may include a flat motor having a shortened axial dimension.
Employing such a flat motor for the motor unit makes it possible to reduce the axial dimension(size), thereby allowing the axial dimension of the entire drive apparatus to be further reduced while the properties of the planetary roller unit are being put to use.
Furthermore, the aforementioned planetary roller unit may be of a frame rotational type having a rotational frame member on an outer periphery of the unit itself. The frame member may be coupled to the ring roller so as to rotate integrally therewith, and the frame member itself may be provided with a pulley for driving the belt.
With this configuration, the need for providing a separate pulley in addition to the drive unit is obviated since the frame member itself, which is rotatably integrally coupled to the ring roller, is provided with a pulley for driving the timing belt. Thus, compared with a drive apparatus having a separate pulley connected thereto, this configuration can make the drive system more compact, simplify the structure, reduce the number of components, and contribute to the reduction of cost.
In this case, the ring roller and the frame member may be integrated with each other by a exterior member 100 penetrating the ring roller to the frame member or an extended portion of the frame member.
With this configuration, the exterior member 100 that penetrates the ring roller is supported with the frame member at both axial ends of the ring roller, thereby making it possible to provide improved rigidity for the integration of the ring roller with the frame member.
In addition, irrespective of the number of stages of the planetary roller units, the ring roller and the frame member can be easily integrated with each other.
Furthermore, the drive apparatus can be configured such that multiple stages of the planetary roller units are provided and the output from the motor unit is received by the sun roller of an initial stage planetary roller unit of the multiple stages of planetary roller units. Moreover, the carrier for supporting the planetary roller of a planetary roller unit of a preceding stage including the initial stage is coupled in turn to the sun roller of a following stage planetary roller unit, and then the carrier of a final stage planetary roller unit is fixed. Still moreover, at least the ring roller of the final stage planetary roller unit is integrally rotatably coupled to the frame member, thereby making the frame member rotatable.
With this configuration, due to the multiple stages of the planetary roller units, it is possible to easily provide a high reduction ratio while preventing the outer diameter of the entire drive apparatus from becoming larger. In addition, since the number of frictional contacts between the rollers is increased, it is possible to improve the safety function provided by the sliding of the rollers, and the performance of absorbing vibrations. Furthermore, arranging a plurality of stages of the planetary roller units side by side in the axial direction improves the bearing function of the planetary roller unit itself, thereby further improving the rotational stability of the frame member.
Furthermore, the drive apparatus may be configured such that the planetary roller unit secures a carrier for supporting the planetary roller to the motor unit, a mounting flange for mounting the drive apparatus to an exterior member 100 is formed on the carrier opposite to the planetary roller unit, and the mounting flange is used as part of a casing of the motor unit.
This configuration requires a smaller space for installation than the configuration in which a separate mounting base is fixedly provided on the motor unit side.
Furthermore, the mounting flange is directly integrated with the carrier of the planetary roller unit. Therefore, the mounting flange can be secured to the exterior member 100 of an elevator cage or the like, thereby making it possible to shorten the distance from the bolt of the mounting flange to where a load is applied to the frame member. This makes it possible to reduce the reactive moment acted upon the mounting base when compared with the configuration in which the separate mounting base is fixedly provided on the motor unit side, thereby making it possible to reasonably design the drive apparatus with high installation stability.
Additionally in this configuration, since the mounting flange formed on the carrier of the planetary roller unit is also employed as a part of the motor unit casing, thereby reducing the number of components. In addition to this, the motor unit and the planetary roller unit can be highly integrated with each other, thereby making it possible to improve the rigidity of the entire apparatus.
In addition, to rotate the frame member and the ring roller integrally, the drive apparatus may be configured such that a bearing is disposed between an outer periphery of the carrier for supporting the planetary roller of the planetary roller unit and an inner periphery of the frame member or an extended portion of the frame member.
That is, when the frame member and the ring roller are rotated integrally, the reactive force or load inputted from the driven member side to the frame member is directly acted upon the ring roller via the frame member. In general, with a simple planetary structure using a traction roller, a load (particularly a thrust load) from the ring roller side impairs smooth rotations of each roller, resulting in increased vibrations or noise. This configuration employs a simple planetary structure using a traction roller to implement xe2x80x9cquietnessxe2x80x9d. Thus, the integral rotation of the frame member and the ring roller would otherwise cause the problem of being subject to an increased bad influence of the load from the frame member.
The following very simple configuration provides a solution to this problem. That is, the bearing is disposed between the outer periphery of the carrier (secured to the exterior member 100) and the inner periphery of the frame member or the extended portion of the frame member.
Such an arrangement of the bearing allows the frame member or an output member to be supported via the bearing directly by the carrier secured to the exterior member 100. Therefore, even when the frame member is acted upon by a load from the driven member side, the load can be received via the bearing, the carrier, and the exterior member 100. This allows the ring roller not to be affected by the load, thereby making it possible to always provide smooth rotations. Incidentally, the extended portion of the frame member is not necessarily extended integrally, and a separate member may be coupled to the frame member to form an xe2x80x9cextended portionxe2x80x9d.
Incidentally, this configuration is also applicable to a power transmission apparatus having multiple stages of planetary roller units. In this case, the sun roller of the initial stage planetary roller unit among the multiple stages of the planetary roller units may be adapted to receive the power inputted from the input shaft. Then, the carrier of the preceding stage planetary roller unit, including the initial stage, is in turn coupled to the sun roller of the following planetary roller unit. Then, the carrier of the final stage planetary roller unit is made securable to the exterior member 100, and at least the ring roller is rotatably coupled in one piece to the frame member, thereby making the frame member rotatable. Then, the frame member is extended in the axial direction from the ring roller of the final stage planetary roller unit to dispose a bearing between the outer periphery of the final stage carrier and the inner periphery of the frame member.
Incidentally, this bearing can also be used such that the axial movement of the frame member is prevented via the bearing with respect to the carrier secured to the exterior member, and due to the presence of the bearing, a transmission of the thrust load acted from the frame member to the planetary roller unit is cut.
In general, a simple planetary structure using the traction roller is characterized in that the thrust load has structurally a more deleterious effect on the structure than the radial load. This structure has the bearing between the carrier and the frame member, and the structure itself is capable of coping with a reactive force in the direction of the thrust to some extent. If, however, such a structure is in particular positively employed in which the axial movement of the frame member with respect to the carrier is prevented via the bearing, the structure makes it possible to rotate the ring roller with stability even when a thrust load is acted upon the ring roller from the frame member side.
Incidentally, in this case, a thrust bearing may not be particularly employed as the bearing itself, that is, a general ball bearing or a roller bearing may be employed. This also makes it possible to provide such a structure as to cope with a thrust load if the bearing is incorporated into the apparatus such that the axial movement of the inner and outer ring of the bearing is positively prevented (for example, via a step, a stopper ring, or the like) with respect to the carrier and the frame member (which will be described later).
On the other hand, it is more preferable to construct the drive apparatus as follows. That is, a flange is fixedly coupled to an end portion of the carrier opposite to the planetary roller unit, the carrier supporting the planetary roller of the planetary roller unit, and a center bearing is disposed about the axial center of the flange. The disposed center bearing supports an end of the motor shaft and the motor shaft is extended to penetrate the carrier and coupled to the sun roller. Furthermore, the center bearing and the bearing function of the planetary roller unit itself are employed to support an output member integrated with the ring roller rotatably around the extended motor shaft.
That is, with this structure, the rotational output from the motor unit is inputted as it is to the sun roller via the motor shaft. On the other hand, the frame member is made rotatable about the extended motor shaft by means of the center bearing and the bearing function of the roller unit itself and is supported by the motor unit in a combined or integrated fashion. Consequently, it is made possible to provide a motor-equipped power transmission unit, which is compact in the axial direction and has a high rigidity of assembly.
Incidentally, the drive apparatus may also be configured such that the motor shaft is extended from the center bearing and supported in a cantilever manner within the casing of the motor unit by the center bearing and the bearing function of the planetary roller unit itself.
This configuration can provide a motor-equipped power transmission unit more compact in the axial direction than the configuration in which another bearing or the like is provided on the end portion of the motor shaft opposite to the center bearing, and the motor shaft is supported at the both axial sides of the rotor (i.e., the configuration for supporting the motor shaft at its both ends).
In addition, only one bearing or the center bearing described above is provided for supporting the motor shaft, thereby reducing the cost of the drive apparatus.
Furthermore, the drive apparatus may also be configured such that a plurality of stages of planetary roller units are arranged side by side on the extended motor shaft, a plurality of ring-shaped plates are arranged so as to contact with part of or entire surface of axial side of the carrier of each stage, and the axial movement of the carrier is restricted by means of the preceding and following ring-shaped plates.
This configuration prevents the skew of the carrier and provides a smoothed rotation and a quiet operation in a power transmission unit including multiple stages of planetary roller units and having a high reduction ratio.
Furthermore, by using the front and reverse of the ring-shaped plate, the axial movement of the carrier and the planetary roller can be restricted with less number of components.
Furthermore, planetary roller unit can be mounted on the extended motor shaft over a long length, thereby stabilizing the support of the output member with respect to the motor shaft.
The nature, principle, and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts are desinated by like reference numerals or characters.